As an organic light-emitting device, there is known a device having a multilayer structure in which a light-emitting layer comprising a phosphorescent low molecular weight compound is provided between a hole transport layer and an electron transport layer. A low molecular weight compound such as a triphenylamine derivative is used in the hole transport layer (see Patent Document 1).
When each of such layers as mentioned above is formed by using a low molecular weight compound, however, vacuum deposition method is generally employed, and there have been problems that vacuum equipment is required, that the film thickness of the layer is likely to be uneven, and that devices with large areas are difficult to produce. In addition, there has been a problem that an organic light-emitting device comprising a light-emitting layer obtained from a phosphorescent low molecular weight compound is inferior in the durability.
Meanwhile, development has also progressed for a phosphorescent polymer which is obtained by copolymerizing a phosphorescent polymerizable compound and an charge transport polymerizable compound. Such a phosphorescent polymer compound has the advantage that the light-emitting layer can be formed by a coating method such as spin coating. For example, Patent Document 2 discloses a copolymer of a triphenylamine derivative and an iridium complex.    [Patent Document 1] JP-A-2003-308978    [Patent Document 2] JP-A-2005-97589